My heater electric pump was intermittent last winter so I pulled to replace brushes a few weeks ago. When I opened it up I still had about 3/16" of brush left. So I wasn't sure that was the issue but I replaced them anyway. It didn't work. In fact the pump was not working more than it was, which was the opposite of the way it was before.
I happened to see in an old post someone using a different pump that's quite a bit cheaper than a used pump OEM pump. The cheapest I found was $110 and I don't know how many miles on the car it came out of. So I bought this guy as an alternative. (thanks to whoever had the suggestion in some old post I found) https://www.ebay.com/itm/333966017883
It's smaller and I had to do some mods to make it work. I ended up cutting the cable and connector off of the old pump and I soldered extension leads onto the new pump and then soldered and added heatshrink and tape to connect them. I cut the bracket off of the old pump to save the hose support and zip tied the pump to the nearby hoses. The hardest part was getting the hoses back on. Very tight fit. I also had to snip away a little plastic around the new pump electrical tabs so I could get better access with my soldering iron. It works great so far. Hopefully that issue is far behind me now. And it was a lot cheaper.